Wafers of semiconductor material such as silicon and gallium-arsenic having formed thereon integrated circuits have a relatively large diameter. In the production of integrated circuits (IC), such a wafer is adhered to an adhesive tape sometimes called a dicing tape, diced into chips (IC chips), which are then released (picked up) from the dicing tape, and adhered to (mounted on) a lead frame by means of an adhesive such as an epoxy resin.
For dicing tapes suitable for use in such a wafer processing technique, is required that they should exhibit a strong adhesion to the semiconductor wafer in the step of dicing the wafer into IC chips on the one hand, while they should also have such a reduced adhesion to the IC chips in the step of picking up the IC chips so that the IC chips may be readily released without carrying adhesive residues from the dicing tapes. Thus, in prior art dicing tapes adhesive and releasing properties, which are conflicting, are required, and use of a dicing tape whose adhesive and releasing properties are not well balanced in wafer processing, invites such a problem that the dicing and/or picking up steps of the process cannot be smoothly carried out. In particular, when a prior art dicing tape is used in wafer processing, a part of the adhesive of the dicing tape is transferred to the picked up IC chips and adversely affects the characteristics of the resulting IC. Accordingly, it has been necessary to remove the undesirable residual adhesive from the IC chips before they are mounted on a lead frame. While complete removal of the residual adhesive is difficult, the step of removing the adhesive not only makes the processing complicated, but also invites a problem of environmental pollution if an organic solvent is used, for the removal of the residual adhesive.
Furthermore, a separate adhesive such as an epoxy resin has been used for mounting the IC chips on a lead frame, as described in Japanese Patent Laid-open Publication No. 60-198,757. The use of a separate adhesive involves another problem such that unceasing application of appropriate amounts of the adhesive is technically very difficult, which results in a case of a very small. IC chip in the applied adhesive frequently bulging out of the chip, whereas in a case of a relatively large IC chip, the amount of the applied adhesive tends to be too small to provide a desired adhesion.